When Is The Best Time To Introduce Solids?

The decision to start solids is both an exciting one (your baby is growing up!) and a difficult one for many parents. The latter is because there’s so much conflicting information floating around (“Starting solids sooner will make your baby sleep better!” “Starting solids too soon will give your baby allergies!”). The purpose of this post is to summarize the research that addresses when to start solids in a baby that is breast- and/or formula-fed.

If you’re confused by all the seemingly conflicting information out there regarding when to start solids, you’re in good company; the American Academy of Pediatrics (AAP) is split on this issue. The AAP’s Breastfeeding Initiatives state that it’s best to wait until an infant is 6 months of age, while the AAP’s nutrition division suggests that it’s fine to introduce solids around 4 months of age. There is no research to suggest that there’s any benefit associated with introducing solids before 4 months of age, and there is quite a bit of research suggesting that such early introduction of solids is associated with increased risk of allergies and eczema (see, for instance, Greer et al, Tarini et al, Zutavern et al). Waiting until 6 months of age to introduce solids decreases the risk of atopic diseases (allergies, eczema, and asthma). Researchers are split on introduction of the most allergenic foods (including eggs, shellfish, and nuts). Some studies (including Filipiak et al) suggest that there’s no benefit associated with waiting beyond the sixth month to introduce these foods (in non-chokable form), while other studies (such as Fiocchi et al) suggest waiting to introduce dairy, egg, nuts, and seafood. Given the split nature of research findings on delayed introduction of highly allergenic foods, it may be worth delaying such foods in families with a history of atopic disease. Highly allergenic foods aside, the preponderance of evidence suggests that the best time to introduce first solid foods falls somewhere between 4 and 6 months of age. The question, then, is whether to shoot for closer to the beginning of that window, or closer to the end.

There are several arguments often made for adding solids to the diet earlier, rather than later. None of these, however, are supported by science. Perhaps the most common assertion is that adding solids will improve infant sleep. Several studies have examined this issue, and have found no sleep improvement with added solids (see, for instance, Macknin et al, Oberlander et al.) The Oberlander study looked at newborns, comparing sleep after a randomly assigned meal of water, carbohydrate, or formula. Water-fed infants slept less than formula-fed infants, while carbohydrate-fed infants (contrary to the common maxim) didn’t sleep as well as formula-fed infants. The Macknin study examined the effects of adding infant cereal to the nighttime bottle (a common practice thought by some to promote sleep) of 5-week-old and 4-month-old infants. The sleep durations of the infants given cereal were compared to the sleep durations of same-age infants given formula with no cereal; the researchers found no increased quantity or quality of sleep with cereal. There is no research support for beginning solids as a means of improving sleep.

Another argument used to support introducing solids at closer to 4 months than 6 months of age is that the older infants are (according to their caregivers) no longer satisfied by breast milk or formula alone. Because 4- to 6-month-olds have very limited communication ability, this is largely based upon speculation. For instance, some caregivers interpret a 4-month-old’s sudden interest in the food on an adult’s plate (or silverware) as an interest in eating. Given the opportunity, many 4-month-olds will grab food off an adult’s plate and place it in their own mouth, interpreted by some caregivers to mean the baby wants to (and/or is ready to) eat solids. However (and I recognize this is not a scientific statement), 4-month-olds also put rocks, garbage, and anything else they can find into their mouths. Around 4 months of age, an infant’s attention begins to turn to the outside world. The infant also increasingly possesses the ability to control his hands, allowing him to grasp objects of interest and bring them to his mouth for exploration. Infants don’t differentiate “food” from “non-food” with regard to what they taste; they simply use oral investigation as one of their means of gaining information about the world. It is a misattribution of intent to suggest that a 4-month-old who grabs food off his mother’s plate wants to eat solids. More scientifically, there is no evidence to suggest that an infant younger than 6 months of age needs anything more than breast milk (with supplemental vitamin D if indicated, see this article for more information) or formula. Further, there is ample scientific evidence showing that infants thrive on nothing but breast milk for the first 6 months (see, for instance, Carruth et al, Dewey, Nielsen et al). There is also evidence showing that introducing solids after 4, but before 6 months of age doesn’t positively affect growth (Cohen et al), because infants fed solids consume less milk or formula. Even infants given as many nursings (this study was conducted on breastfed infants) as they’d been given prior to introduction of solids consumed less milk per nursing when given supplemental solids. This demonstrates that a 4-month-old can’t be made to increase his caloric intake by giving him solids, as he’ll take less milk in response. Of particular concern is the case of the breastfed infant; there is no substance as nutritionally complete or suited to the digestive tract of the young infant as breast milk. Thus, since the breastfed infant responds to solids by decreasing milk consumption, supplementing with solids prior to 6 months of age actually decreases the quality of the breastfed infant’s diet. Given that formula is designed to mirror the nutritional qualities of breast milk as much as possible, we can reasonably extrapolate that it is the best second choice for feeding a non-breastfed infant (or supplementing an infant whose mother is not exclusively breastfeeding) until 6 months of age, and that introduction of complementary solids displaces a higher-quality source of nutrition.

If waiting until 6 months to introduce solids is good, then, is waiting longer than 6 months even better? Apparently not. There’s research that suggests rather strongly that delaying the introduction of solids beyond the 6-month point does not further decrease the risk of allergies (see, for instance, Filipiak et al, Greer et al, Zutavern et al), and may even increase the risk (Nwaru et al). Further, breast milk and formula are no longer sufficient to support increasing nutrient needs beyond 6 months of age (Dewey). As an isolated (but not unique) example, breast milk is quite low in iron (there is a great article about this at Science of Mom), and complementary foods can be used to increase iron in the diet (there’s another great article from Science of Mom here). The most nutritionally-complete diet for a 6-month-old (or older) infant should consist of mainly breast milk (or formula), with carefully-selected complementary solid foods.

 

Science Bottom Line:* There is ample research to support waiting until after 4 months of age to begin complementary solids, and there is a modest amount of research to support waiting until 6 months of age, particularly in the case of a breastfed infant. There is no evidence of any nutritional or behavioral benefit conferred by solids between 4 and 6 months of age. Research does not support (and, in fact, opposes) waiting beyond 6 months of age to introduce complementary solids.

 

When did you/will you introduce solids, and why?

 

References:

Carruth et al. Addition of supplementary foods and infant growth (2 to 24 months). J Am Coll Nutr. 2000 Jun;19(3):405-12.

Cohen et al. Effects of age of introduction of complementary foods on infant breast milk intake, total energy intake, and growth: a randomised intervention study in Honduras. Lancet. 1994 Jul 30;344(8918):288-93.

Dewey, K. Nutrition, Growth, and Complementary Feeding of The Brestfed InfantPediatr Clin North Am. 2001 Feb;48(1):87-104.

Filipiak et al. Solid food introduction in relation to eczema: results from a four-year prospective birth cohort study. J Pediatr. 2007 Oct;151(4):352-8. Epub 2007 Aug 23.

Fiocchi et al. Food allergy and the introduction of solid foods to infants: a consensus document. Ann Allergy Asthma Immunol. 2006 Jul;97(1):10-20; quiz 21, 77.

Greer et al. Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Timing of Introduction of Complementary Foods, and Hydrolyzed Formulas. Pediatrics. 2008 Jan;121(1):183-91.

Macknin et al. Infant sleep and bedtime cereal. Am J Dis Child. 1989 Sep;143(9):1066-8.

Nielsen et al. Adequacy of Milk Intake During Exclusive Breastfeeding: A Longitudinal Study. Pediatrics. 2011 Oct;128(4):e907-14. Epub 2011 Sep 19.

Nwaru et al. Age at the Introduction of Solid Foods During the First Year and Allergic Sensitization at Age 5 Years. Pediatrics. 2010 Jan;125(1):50-9. Epub 2009 Dec 7.

Oberlander et al. Short-term effects of feed composition on sleeping and crying in newborns. Pediatrics. 1992 Nov;90(5):733-40.

Tarini et al. Systematic Review of the Relationship Between Early Introduction of Solid Foods to Infants and the Development of Allergic Disease. Arch Pediatr Adolesc Med. 2006 May;160(5):502-7.

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8 Comments (+add yours?)

  1. Ashley @ C is for Cockerham
    Mar 12, 2012 @ 15:49:24

    We started with baby-led weaning just before 6 months, but T didn’t take a large amount of calories through solids until closer to 8 months. He was and is still exclusively breastfed at almost 12 months. He was a terrible sleeper for the first nine months, and I got SO SICK of hearing how he needed a bottle of formula or rice cereal to help him sleep. Thank you for putting all of the research in one simple place. I’m sure I’ll refer other moms her as well!

    Reply

    • Ashley @ C is for Cockerham
      Mar 12, 2012 @ 15:57:18

      Oh, and my reason for choosing baby-led weaning (BLW) is that it made sense to me. I read about how the mouth, tongue, and jaw develop. Giving a baby chunks of soft food to chew before swallowing was logical vs. swallowing purees before learning to chew. I found that this style of feeding also fit our lifestyle well, as he was able to eat most of the fresh fruits, veggies, and meats we already consumed for our adult meals. T was also good with other motor skills (rolling over, sitting up, crawling, etc.), and I trusted his ability to chew and swallow. I won’t say my family members had the same comfort, but I am very happy I stuck to my guns with nursing and soft solids (no rice cereal, formula, or purees). I now have a thriving almost 1 year old who still loves momma’s milk and all kinds of solid foods.

      Reply

      • Melissa
        Oct 02, 2012 @ 11:30:56

        I also followed Baby-Led Weaning (although we did a little bit of pureed food for daycare) and found it to be a great way to introduce solids to my daughter. We started a bit after six months, and she was still an enthusiastic breast-feeder, so I didn’t really worry too much about how it all balanced out, as long as I was giving her nutritious, whole foods. Now she’s a super adventurous eater compared to her peers and enjoys a ton of different (and very strongly flavored foods). She has great fine motor skills as well – all of which I attribute to BLW.

      • SquintMom
        Oct 03, 2012 @ 08:10:55

        I’m glad you had a good experience! I worried a little about BLW and choking, so we did a modified approach, and I don’t like the fact that the BLW books present opinion as scientific fact (there’s no scientific support for BLW currently; benefits are speculative), but I still think it’s an approach that has merit for some. Kudos for going with your gut and finding something that worked!

  2. BabyAttachMode
    Mar 12, 2012 @ 16:29:48

    Interesting post! We started solids at 5.5 months, but we mostly give him pieces of food instead of purees, so it took a while before he actually ate anything.
    Related to that: I’ve heard people say that babies need to be able to sit up by themselves and put food in their mouth by themselves before you’re supposed to start solids (i.e. those signs show that they are ready). Is there any scientific evidence for that?

    Reply

  3. Miranda
    Mar 15, 2012 @ 11:16:15

    I also wonder if baby should be sitting up on her own before foods are introduced. It seems like as good a benchmark as any (and as you pointed out, better than the “reaching for food so must instinctively want food” mark). It’s sad to me that there seems to be so much pressure, once baby is 4 months old, to go ahead and start solid foods, with the only justification being “Why not?” We don’t need to push them to grow up so fast.

    Reply

    • SquintMom
      Mar 15, 2012 @ 17:56:56

      Hmmm. Well, I think MOST babies are sitting by 6 months, and I also think there’s enough evidence to suggest that it’s better to wait until 6 months (rather than 4) that this shouldn’t be an issue. I wonder what a pediatrician would suggest for a 6-mo-old who isn’t sitting, though…

      Agreed that there’s too much pressure for them to grow up! They do that pretty darn fast on their own!

      Reply

  4. melinda
    Jun 03, 2012 @ 05:01:35

    My health care nurse said wait until 6 months but the ladies in my mothers group emphatically promoted the idea of rice cereal @ 4 months as a means of readying baby for solids. This had painful & traumatic results for bub & her doting parents. Manually helping her to pass stools over the course of several days, the texture & colour of dried clay was just horrific. Next baby we’ll wait until @ least 5 months & veges will be the first trial. NO RICE CEREAL!

    Reply

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